Microvane Arrays for Wingtip Vortex Mitigation

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Solution Overview

Problem

Wake turbulence caused by well-defined vortices at the edges of aircraft wings and airfoils persists due to the formation of a strong vortex core, which can lead to safety issues for trailing aircraft, and existing solutions like winglets add drag while attempting to dissipate these vortices.

Innovation Solution

The use of flow directors positioned on the low-pressure surface of airfoils to redirect freestream air and form co-rotating vortices that diffuse the main tip vortex core, weakening it and hastening its dissipation without significantly affecting lift.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If winglets or wing-tip extensions are used to prevent vortex core formation, then vortex persistence is reduced, but drag increases

Engineering Contradiction:

Improvevortex persistenceVSAvoiddrag

Core Design Contradiction:

Duration of action of stationary objectVSLoss of energy

Solution Approach 1:

The invention segments the continuous vortex core into discrete portions by introducing spanwise flow through microvanes. This breaks up the coherent vortex structure into smaller, less persistent vortical structures, reducing overall vortex persistence without requiring large wing modifications that would increase drag

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The microvanes are positioned specifically at the wingtip region where vortex formation occurs, applying the flow disruption function locally rather than across the entire wing span. This localized approach minimizes drag penalties while effectively addressing vortex persistence at the critical tip region

Inventive Principle:

Principle #3Local quality

2Duration of action of stationary object

If wing thickness is increased to impede streamline rolling, then vortex core definition is reduced, but device complexity increases

Engineering Contradiction:

Improvevortex persistenceVSAvoidairfoil structure

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The microvanes act as intermediary elements that mediate between the upper and lower surface flows at the wingtip. Instead of modifying the fundamental airfoil structure, these intermediate devices introduce spanwise flow to disrupt vortex core formation while maintaining the original wing geometry and avoiding increased device complexity

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively reduces the longevity of airfoil tip vortices, enhancing aircraft performance by minimizing wake turbulence and reducing the risk to following aircraft, while maintaining lift and minimizing drag penalties.

Implementation Method 1

flow directors configured and positioned to re-direct freestream air over a low pressure surface of an airfoil in such a way as to displace and weaken a main tip vortex

Methodology Applied

Scientific EffectVortex diffusion: Vortex Ring

Implementation Method 2

redirect freestream air and form co-rotating vortices that diffuse the main tip vortex core

Methodology Applied

Scientific EffectCo-rotating vortex formation: Vortex Ring

Data Source

PatentUS9896192B2Minimally intrusive wingtip vortex wake mitigation using microvane arrays

Publication Date: 2018.02.20 LOCKHEED MARTIN CORP

AI summary

An airfoil tip vortex mitigation arrangement comprising one or more flow directors configured and positioned to re-direct freestream air over a low pressure surface of an airfoil in such a way as to displace and weaken a main tip vortex generated at a tip of the airfoil.